Fluid-moving device with an internal passageway and a clearance seal

ABSTRACT

A fluid-moving device is disclosed. The fluid-moving device comprises a housing defining a suction chamber; at least one internal passageway formed inside the housing; a moving member movably disposed within the chamber; and a sealing member circumferentially disposed between the housing and the moving member. The internal passageway has a first end opening to the suction chamber and a second end connecting to an outside surface of the housing. The sealing member has a fluid-tight relationship with the housing. The sealing member and the moving member define a continuous and uniform gap, having a size that allows the fluid to fill the gap but prevents the fluid from flowing through the gap from the first side to the second side of the opening under an operating pressure differential between the first and the second side.

This application is a continuation-in-part of U.S. patent application Ser. No. 09/685,474 filed Oct. 10, 2000 and U.S. patent application Ser. No. 09/685,307 filed Oct. 10, 2000. BACKGROUND OF THE INVENTION

1. Area of the Art

The invention relates generally to fluid-moving devices. More particularly, the invention is directed to fluid-moving devices, such as piston pumps, with fluid-tight dynamic clearance seals and internal passageways for connecting the fluid-moving device to secondary devices.

2. Description of the Prior Art

In many types of fluid-moving equipment, such as liquid pumps, slurry pumps, dry mixers, and numerous other devices, a sliding plunger, rod, piston, or another similar member, reciprocally moves inside a stationary bearing. Typically, fluid leakage around the moving member is prevented by utilizing sealing structures. The material of the sealing structure is required to have some resiliency to permit the moving member to slide back and forth through the axial opening of the sealing structure. On the other hand, the material of the sealing structure is required to possess some degree of stiffness to prevent, or at least minimize, leakage of the liquid around the moving member.

One type of a conventional sealing structure is a mechanical face seal. Typically, the mechanical face seal consists of one seal ring rotating with the driving shaft and one stationary seal ring attached to the surrounding housing. The two seal rings are pressed towards each other by a biasing force which, in this way, prevents liquid from passing between them. For example, U.S. Pat. Nos. 3,282,235; 4,754,981; and 5,772,217 describe a seal with a spring for providing the biasing force. Usually, additional elastomeric components are required to seal each ring from the shaft or housing, correspondingly. Typically, a thin lubricating film is required between the seal surfaces to prevent their damage by dry friction. Nevertheless, with time, wear and vibrations cause the mating faces of the sealing rings to become scored, resulting in leakage of the process fluid. Environments where the process fluid is abrasive or contains a coagulant are particularly damaging to the conventional seals and require their frequent replacement.

A packed stuffing box is another example of a conventional seal for a moving member. This type of seal has been disclosed, for example, in U.S. Pat. Nos. 3,659,862 and 5,333,883. Generally, the packing is sufficiently compressed to limit the passage of fluid through the packing, but not so compressed as to create excess friction between the packing and the moving member. Pressure is generally maintained on the packing by manually tightening a gland on the stuffing box until the point where leakage through the packing is minimized, yet before the point where friction between the packing and the shaft creates overheating of the packing.

Such seal configuration operates on the principle of controlled leakage to the atmosphere rather than zero leakage. This approach, however, requires frequent adjustments, which may result in over tightening of the seal. An over tightening leads to excess friction and heat buildup, excessive wear to the packing, and possibly even damage to the moving member. Even when the pressure on the packing is properly regulated, the pressure necessary to minimize the passage of fluid through the packing causes relatively high friction between the packing and the shaft. As a result, the packing wears out quickly and requires a frequent replacement.

Finally, referring to FIG. 1, a combination of an elastomeric O-ring 1 with a spring preloaded polymer seal 2 has been utilized in the past to create a dynamic seal between a moving member, such as a piston 3, and a housing. For example, Beckman Instruments (Fullerton, Calif.) uses this arrangement in the Access Immunoassay Analyzer. Typically, the housing includes a casing 4 and a piston-supporting bearing 5. The polymer seal 2 prevents the fluid from flowing between the piston 3 and the bearing 5, while the O-ring 1 seals off the housing. A preloading spring 6 forces the polymer seal 2 to squeeze directly on the piston 3 to accomplish the seal, thus resulting in wear of the polymer. The speed of the moving member and the fluid being sealed determines the required frequency of the polymer seal replacement.

Apparently, the sealing structures of prior art do not provide reliable and long-lasting seals between moving members and their housing. The conventional seals undergo a lot of wear during normal operation and have to be replaced frequently. The necessity to replace seals makes prophylactic maintenance of the equipment more laborious and increases its maintenance costs.

Another common problem of fluid-moving equipment is associated with the use of connecting tubing and fittings for connecting secondary devices, such as input/output valves, to the pump. As the fluid passes through each connection, pump to fitting, fitting to tubing, etc., the fluid flow is disturbed and the accuracy and precision of the fluid-moving equipment are adversely affected. Also, depending on the selected tubing type and operating pressure, the tubing may flex and bend, thus disrupting the fluid flow even more and further affecting the dispensing accuracy of the fluid-moving equipment.

Automated analytical instruments are broadly used in chemical, biological, and clinical laboratories, often for testing small sample volumes. When dealing with small volumes or diluted samples, even a minute change in sample dispensing accuracy may lead to substantial analytical errors. When conventional pumps are utilized for sample dispensing in an analytical instrument, the tubing and the fittings between the pump and the input/output valves require frequent maintenance checks for leaks and flow obstructions in order to provide a reliable operation of the instrument. Also, the worn-out tubing and fittings have to be replaced promptly.

Therefore, the conventional fluid-moving equipment does not provide consistent and accurate fluid dispensing, unless the connecting fittings and tubing are adjusted or replaced frequently. Consequently, the maintenance of the conventional fluid-moving equipment is laborious and costly, particularly when the equipment is used for processing large sample batches, diluted samples, or small sample volumes.

SUMMARY OF THE INVENTION

Accordingly, it is an objective of the present invention to provide a fluid-moving device which avoids the undesirable features of the prior devices. Particularly, it is an object of the present invention to provide fluid-moving devices utilizing seals which have a low wear, may be produced at relatively low costs, and provide superior performance in use. It is a further object of the present invention to provide fluid-moving devices without tubing and fittings for connecting to secondary devices such as valves.

These and other objects are achieved in a fluid-moving device of the present invention. The fluid-moving device comprises a housing defining a suction chamber; at least one internal passageway formed inside the housing; a moving member movably disposed within the chamber; and a sealing member circumferentially disposed between the housing and the moving member. The internal passageway has a first end that opens to the suction chamber and a second end that opens to an outside surface of the housing. The sealing member has a fluid-tight relationship with the housing. The sealing member and the moving member define a continuous and uniform gap, having a size that allows the fluid to fill the gap but prevents the fluid from flowing through the gap from the first side to the second side of the opening under an operating pressure differential between the first and the second side.

In one embodiment, both the sealing member and the moving member are made of a ceramic material. The fluid-moving device may also include a static seal disposed between the housing and the sealing member to allow a variable clearance therebetween while maintaining the fluid-tight relationship between the sealing member and the stationary member.

The fluid-moving device of the present invention may be connected to or integrated with a secondary device or structure by utilizing passageways formed in the housing instead of conventional tubing. In one embodiment, the secondary device is a valve with at least one fluid communication port. The fluid communication port of the valve is connected to the second end of the internal passageway. The valve may be mounted on the housing. Alternatively, a valve chamber may be provided in the housing and the valve may be positioned in the valve chamber, at least partially. The fluid-moving device of the present invention may also include valve passageways formed inside the housing. The valve passageways provide a fluid communication between fluid communication ports of the valve and the outside.

In another aspect, the invention provides a pump. The pump comprises a housing having an internal wall defining a suction chamber for containing a fluid; a piston movably disposed within the chamber; a valve, an internal passageway formed inside the housing; and a sealing member circumferentially disposed between the housing and the piston. The internal passageway has a first end opening to the suction chamber and a second end connecting to the valve. The sealing member has a fluid-tight relationship with the housing. The sealing member and the piston define a continuous and uniform gap having a size that allows the fluid to fill the gap but prevents the fluid from flowing through the gap from the suction chamber to an outside of the chamber under an operating fluid pressure.

In a further aspect, the invention provides a method of making a fluid-moving device. The method comprises: (a) providing a housing having a suction chamber; (b) movably disposing a moving member within the chamber; (c) forming an internal passageway, wherein a first end of the internal passageway opens to the suction chamber and a second end of the internal passageway connects to an outside surface of the housing; and (d) placing a sealing member between the housing and the moving member to result in a fluid-tight relationship between the sealing member and the housing, whereby the sealing member and the moving member define a continuous and uniform gap, wherein the gap has a size that allows the fluid to fill the gap but prevents the fluid from flowing through the gap from the suction chamber to an outside of the chamber under an operating fluid pressure.

By eliminating a direct contact between the sealing member and the moving member and by eliminating tubing and connectors between secondary devices, such as valves, and the pumping structure, the present fluid-moving device alleviates many of the problems associated with the conventional devices discussed above. In particular, the advantages of the present fluid-moving device include a minimal wear of the sealing member, a greater precision of fluid-delivery, simplified assembly and maintenance, significantly improved reliability, and a decreased maintenance cost. The device is well suited for use in any system that requires drawing, moving, and dispensing of fluids.

The invention may be particularly advantageous for use in high-precision pumps employed in analytical instrumentation. For example, a piston pump with a clearance seal and an integrated valve manufactured in accordance with the present invention may be beneficially utilized for sample aspiration and dispensing in Nexgen Access System (Beckman Instruments, Calif.), disclosed in a U.S. patent application titled “Method and System for Automated Immunochemistry Analysis,” Ser. No. 09/815,088, filed Mar. 16, 2001, which has been commonly assigned to the assignee of the present invention and relevant parts of which are incorporated by reference herein.

The invention is defined in its fullest scope in the appended claims and is described below in its preferred embodiments.

DESCRIPTION OF THE FIGURES

The above-mentioned and other features of this invention and the manner of obtaining them will become more apparent, and will be best understood by reference to the following description, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of a conventional piston seal assembly.

FIG. 2 is a cross-sectional view of a clearance seal, according to one embodiment of the present invention.

FIG. 3 is a cross-sectional view of a clearance seal, according to another embodiment of the present invention.

FIG. 4 is a schematic representation of a fluid-moving device, according to one embodiment of the present invention.

FIG. 5A is side sectional view of a piston pump with an integrated valve and a manifold, according to one embodiment of the present invention.

FIG. 5B is a top view of a piston pump with an integrated valve and a manifold according to one embodiment of the present invention. The view shows a placement of a section line 8B-8B to obtain FIG. 8B.

FIG. 5C is a side view of a piston pump with an integrated valve of FIG. 5B. The view shows a placement of section lines 6-6, 7-7, and 8A-8A to obtain FIGS. 6, 7, and 8A, respectively.

FIG. 6 is a side view of the piston pump with an integrated valve and a manifold shown in FIG. 4 with a partial side section depicting the valve and the manifold passageways connecting a valve inlet with a fluid input port on the manifold, in accordance with one embodiment of the present invention.

FIG. 7 is a side view of the piston pump with an integrated valve and a manifold shown in FIG. 4 with a partial side section depicting the valve and the manifold passageways connecting a valve outlet with a fluid output port on the manifold, in accordance with one embodiment of the present invention.

FIGS. 8A and 8B are partial side sectional (8A) and cross-sectional (8B) views of the piston pump of FIG. 4 showing an internal passageway formed inside the housing, according to the present invention.

DETAILED DESCRIPTION

The present invention provides a fluid-moving device with a clearance seal and an internal passageway for connecting a suction chamber of the fluid-moving device to the secondary structures such as valves. The fluid-moving device of the present invention may be any device having a housing defining a suction chamber and a moving member reciprocating in the chamber. Examples of such devices include, but are not limited to, dispensing pumps, slurry pumps, and impeller pumps, used in a broad range of applications. The moving member may be, for example, a sliding plunger, rod, or piston. While a particular configuration of the invention may take on different or modified forms, a piston pump will be used to illustrate the invention in more detail. The fluid-moving device of the present invention may be used for pumping and dispensing any suitable fluid, including biological fluid samples, such as buffer solutions, reagents, patient samples.

FIG. 1 illustrates a conventional seal assembly 10 of a piston pump. Typically, the piston pump includes a housing defining a suction chamber 100. The housing includes a stationary casing 4 and a stationary piston-supporting bearing 5. A piston 3 reciprocates within the suction chamber and is supported by the bearing 5 circumferentially disposed between the casing and the piston. The conventional seal assembly includes a spring-preloaded polymer seal 2 disposed between the bearing 5 and the piston 3. A preloading spring 6 forces the polymer seal 2 to squeeze on the piston 3 and the bearing 5 to form two sealing points, 7A and 7B, and to prevent a fluid from leaking into a clearance 8 between the piston and bearing. Typically, an additional elastomeric O-ring 1 is placed under a compression between the bearing 5 and the casing 4. The O-ring forms a sealing point 9A with the bearing and a sealing point 9B with the casing to prevent the fluid from running into a clearance 11 between the bearing and the casing. Consequently, the fluid fills the clearances 12 and 13 of the suction chamber 100, but cannot flow into clearances 8 and 11 on the outside of the chamber. However, as discussed above, due to the required contact between the stationary polymer seal 2 and the moving piston 3 at the sealing point 7A, the conventional seal assemblies suffer from rapid deterioration of the polymer seals and require their frequent replacement.

The present invention solves the problems of prior art by providing a clearance seal, which does not require a direct contact between the piston and the sealing member. Referring to FIG. 2, a fluid-moving device of the present invention, such as a piston pump, includes a stationary housing 21 with an internal wall 22 defining a suction chamber 23 for containing a fluid being pumped. A moving member, such as piston 24, is movably disposed within the suction chamber. A sealing member 25 is circumferentially disposed between the housing 21 and the piston 24 and has a fluid-tight relationship with the housing. The sealing member and the piston define a continuous and uniform gap 26. The gap 26 has a size that allows the fluid to fill the gap but prevents the fluid from flowing through the gap from the suction chamber to an outside of the chamber under an operating fluid pressure.

For the purposes of the present invention, “a fluid-tight relationship” between two structural elements means that the fluid cannot pass therebetween. It would be appreciated by those skilled in the art that any sealing method between the sealing member 25 and the housing 21 may be used, as long as it provides a reliable seal. For example, in one embodiment shown in FIG. 2, a fluid-tight relationship between the sealing member 25 and the housing 21 is accomplished by utilizing a removable elastomeric seal, such as an O-ring 27. In another embodiment shown in FIG. 3, the sealing member 25 is integrally formed with the housing 21. In this embodiment, the sealing member may be molded together with the housing from the same material. Alternatively, the sealing member may be made of a different material than the housing and attached to the housing. Means and methods of attachment of two members are well known in the art and will not be discussed.

Referring to FIGS. 2 and 3, for the purposes of the present invention, a “continuous gap” means that the sealing member and the piston do not have any points of direct contact. A “uniform gap” means that the distance between the piston and an internal wall 28 of the sealing member does not vary significantly so-as to compromise the hydraulic seal formed therebetween. It would be appreciated by those skilled in the art that such a uniform gap requires closely controlled radial dimensions of an outer wall 29 of the piston and the internal wall 28 of the sealing member and a high assembling precision. Consequently, to simplify the control of the critical gap 26, in the preferred embodiment, the cross-sections of the internal and the outer walls 28 and 29 have substantially circular shapes. Materials that have a high hardness and can be machined with a great precision may be used to make the sealing member and the piston and would be known to those of ordinary skill in the art in view of this disclosure. In one embodiment, both the sealing member and the piston are made of ceramic materials.

It is an unexpected discovery by the present inventors that a fluid seal can be formed between a moving and a stationary member without a direct contact therebetween. It has been observed that the size of the gap 26 may be selected to allow the fluid to fill the gap between the seal and piston, thus avoiding a dry friction, but to prevent the fluid from flowing through the gap. It may be hypothesized that when the clearance gap is sufficiently small, the adhesive forces of the fluid toward the piston and the seal are greater than the force exerted by the fluid due to an operating pressure, thus preventing the fluid from flowing through the gap.

The ranges of suitable sizes of the gap 26 depend on the physical properties of the fluid being pumped, such as viscosity, surface tension, adhesive force, and operating pressure. Low viscosity fluids will typically require a smaller gap 26 than higher viscosity fluids. Generally, the higher viscosity of a fluid, the broader the range of the gaps 26 that may be used. It should be recognized that the size of the gap greatly depends on a type of application. Those skilled in the art can easily select the size of the gap to accommodate fluids and operating pressures used in a particular application without undue experimentation in view of the instant disclosure.

Referring to FIGS. 2 and 5A, the housing 21 of the pump of the present invention may include a casing 21A defining the suction chamber 23 and a bearing 21B. The bearing has an elongated aperture 51. A moving member, such as a piston 24, is disposed coaxially and slidably inside the aperture 51. A static seal 27 may be further disposed between the casing and the sealing member to provide a fluid-tight relationship between the casing and the sealing member.

As shown in FIG. 2, in one embodiment, the static seal member is an annular elastomeric seal removably mounted under compression, forming a sealing point 31A with the casing and a sealing point 31B with the sealing member. Comparing FIGS. 1 and 2, it is apparent that the sealing of the present invention is more reliable than that of the prior art as it has fewer contact sealing points, which are potential sources of fluid leaks. Referring to FIG. 2, it should be understood that a precise position of the static seal 27 is not important, as long as it prevents fluid from flowing between the housing and the sealing member.

Although the invention is described with a particular reference to a piston pump, it should be recognized that the general features of the clearance seal may be utilized in any device having a stationary member, such as the housing 21, with an opening, such as suction chamber 23, and a moving member, such as piston 24, moveably disposed through the opening. Generally speaking, the stationary member may have any shape so long as it defines two volumes, such as inside and outside of the pump, connected by the opening. The two volumes may contain different fluids and/or be under different pressures (e.g., operating fluid pressure inside the pump and atmospheric pressure outside the pump).

Referring to FIG. 4, in addition to the clearance seal (not shown in FIG. 4), the fluid-moving device of the present invention further comprises an internal passageway 30 formed inside the housing 21. The internal passageway has a first end 32 that opens to the suction chamber 23 and a second end 34 that opens to an outside surface of the housing or connects to one or a plurality of secondary structures, such as valves and manifolds. In one embodiment, shown in FIG. 4, the second end 34 is connected to a fluid communication port 36A of a valve 38. Any type of valve or other secondary structure may be integrated in accordance with the present invention, which will be evident to those skilled in the art. Examples of valves that may be integrated include, but are not limited to, face shear valves, diaphragm valves, and cup-type shear valves.

For the purpose of this invention, the terms “connecting” and “providing a fluid communication” between two parts means connecting them in such a way that a fluid-tight seal is formed and substantially no fluid flow obstruction is created. The internal passageway may be directly connected to a secondary structure by extending the second end 34 through the housing. Alternatively, the internal passageway may be connected to the secondary structures indirectly, by utilizing additional passageways as will be described later.

The operation of the fluid-moving device of the present invention doesn't differ from the operation of conventional fluid-moving devices. As shown in FIG. 5A, the piston 24 is driven by a motor 53 through a piston shaft 54. A reciprocal movement of the piston 24 produces the suction of a fluid from an inlet circuit 60, shown in FIG. 6, and delivery of the fluid to a delivery circuit 70, shown in FIG. 7. The inlet and delivery circuits are discussed in detail below.

The housing 21 of the present invention may be made of any solid material. Preferably, the housing is made from a rigid material that does not visibly deform during operation, thus further improving accuracy and precision of the instant fluid-moving device. Examples of such rigid materials include metal and certain plastics. The suction chamber and the suction passageway may be machined, for example, drilled, in the housing. Alternatively, the housing may be made of two mating parts. Each part has a suction cavity and an internal groove formed between the suction cavity and the outside surface of the housing. The cavity and the groove on one mating part cooperate with the matching cavity and groove on the second mating part to form the suction chamber and the internal passageway. The grooves and cavities may be molded or machined. The methods and means of assembling two cooperating structures are well known in the art.

Referring to FIGS. 8A and 8B, in one embodiment, the suction passageway 30 is formed by intersecting bores, for example, 30A, 30B, and 30C in the housing 21. The outer portions 51A (not shown), 51B, and 51C of the bores, opening to the outside surface 52 of the housing, are plugged with plugs 83. The bores may be machined, for example, drilled, molded or produced by any other method, as long as the obtained bores are sufficiently smooth to have a minimal effect on the fluid flow. The plugs 83 may be made of any material providing a fluid- and air-tight blocking of the outer portions of the bores.

Referring to FIG. 4, in one embodiment, the valve 38 is mounted on the housing 21. The valve has at least one fluid communication port 36A connected to the second end 34 of the internal passageway 30, whereby the pressure generated in the suction chamber is communicated to the valve 38. In another embodiment, a valve chamber 39 is formed in the housing 21. The valve chamber 39 accommodates, at least partially, the valve 38.

The fluid-moving device of the present invention may have an integrated valve with a plurality of fluid communication ports 36, each port connected to the internal passageway 30. Preferably, as shown in FIG. 4, at least one communication port 36B is a fluid inlet, and at least one communication port 36C is a fluid outlet.

Referring to FIGS. 6 and 7, in another embodiment of the present invention, the fluid-moving device further comprises a fluid inlet circuit 60 and a fluid delivery circuit 70 formed inside the housing 21. The fluid inlet circuit 60 comprises a valve passageway 61 connecting the valve inlet 36B to the outside surface 52 of the housing 21. The fluid delivery circuit 70 comprises a valve passageway 71 connecting the valve outlet 36C to the outside surface 52 of the housing 21. Each valve passageway has a first end 63 or 73 connected to the inlet 36B or the outlet 36C, respectively, and a second end 64 or 74 opened to the outside. The valve passageways 61 and 71 may be machined, for example, drilled, in the housing. Alternatively, the housing may be made of two mating parts, as described above, with molded or machined matching grooves cooperating to form valve passageways.

The fluid-moving device of the present invention may be connected to fluid supplies and sinks utilizing any appropriate interface. Preferably, the interface should create a minimal effect on the fluid flow. Referring to FIGS. 4, 6, and 7, in the most preferred embodiment, a manifold 35 is used as an interface, which provides a reliable and low fluid-flow-obstructing connection to fluid sources and sinks. The manifold 35 connects the second outer ends 64 and 74 of the valve passageways 61 and 71 with a fluid cavity 67 and output ports 47, respectively.

Referring to FIGS. 1, 6 and 7, the manifold comprises a casing 78 and an internal fluid cavity 67, which serves as a fluid supply reservoir. The manifold has at least one manifold input port 37 and at least one output port 47. The manifold ports are disposed within the casing 78 and exposed to the outside. The manifold 35 further comprises a plurality of internal manifold passageways 62 and 72 formed in the manifold casing 78. The manifold passageway 62 connects the outer end 64 of the valve passageway 61 with the manifold input port 37. The manifold passageway 72 connects the outer end 74 of the valve passageway 71 with the manifold output port 47. In some embodiments requiring more than one fluid source and more than one fluid sink and having a valve with a plurality of inlets and outlets, separate manifold and valve passageways may be formed to accommodate each fluid source and sink.

One or more housings may be attached to the manifold by any appropriate method, as long as it provides a secure and fluid-tight assembly. Examples of attachment methods include, but are not limited to, securing with fasteners, such as nuts and bolts or screws, clamps, and latches. These and other methods and means of assembling two structures are well known in the art and, therefore, are not illustrated in the accompanying figures.

The connection between the valve and the manifold passageways is preferably fluid-tight. It would be appreciated by those skilled in the art that any sealing method between the valve and the manifold passageways may be used as long as it provides a reliable seal. For example, in one embodiment, an elastomeric seal, such as an O-ring 65, is positioned between the valve and the manifold passageways of the inlet circuit 60, and an elastomeric seal, such as an O-ring 76, is positioned between the valve and the manifold passageways of the delivery circuit 70.

Another aspect of this invention is directed to a method of making a fluid-moving device. The method comprises: (a) providing a housing having a suction chamber; (b) movably disposing a moving member within the chamber; (c) forming an internal passageway, wherein a first end of the internal passageway opens to the suction chamber and a second end of the internal passageway opens to an outside surface of the housing; and (d) placing a sealing member between the housing and the moving member to result in a fluid-tight relationship between the sealing member and the housing, whereby the sealing member and the moving member define a continuous and uniform gap, wherein the gap has a size that allows the fluid to fill the gap but prevents the fluid from flowing through the gap from the suction chamber to an outside of the chamber under an operating fluid pressure.

Referring to FIGS. 8A and 8B, the step of forming an internal passageway inside the housing may be accomplished by making intersecting bores, for example, 30A, 30B, and 30C, in the housing. Then, outer portions 81A, 81B, and 81C of the bores, which are adjacent to the outside surface 52 of the housing, are plugged with plugs 83.

The present invention may be embodied in other specific forms without departing from its essential characteristics. The described embodiment is to be considered in all respects only as illustrative and not as restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of the equivalence of the claims are to be embraced within their scope. 

1. A fluid-moving device, comprising: a housing defining a suction chamber and at least one internal passageway formed inside the housing, the internal passageway having a first end opening to the suction chamber and a second end opening to an outside surface of the housing; a moving member movably disposed within the chamber; and a sealing member circumferentially disposed between the housing and the moving member, the sealing member having a fluid-tight relationship with the housing, and the sealing member and the moving member defining a continuous and uniform gap, wherein the gap has a size that allows the fluid to fill the gap but prevents the fluid from flowing through the gap from the suction chamber to an outside of the chamber under an operating fluid pressure.
 2. The fluid-moving device of claim 1, further comprising: a bearing disposed inside the suction chamber, the bearing having an aperture, wherein the moving member disposed coaxially and slidably inside the aperture, whereby a reciprocal movement of the moving member generates a pressure inside the suction chamber.
 3. The fluid-moving device of claim 1, wherein the internal passageway is formed by intersecting bores, each bore having an outer portion opening to the outside surface of the housing, wherein the outer portion of each bore is plugged.
 4. The fluid-moving device of claim 1, further comprising a valve mounted on the housing, the valve having at least one fluid communication port connected to the second end of the internal passageway.
 5. The fluid-moving device of claim 4, further comprising a valve chamber formed in the housing, wherein the valve is at least partially situated inside the valve chamber.
 6. The fluid-moving device of claim 5, wherein the valve comprises a plurality of the fluid communication ports, each port connected to the internal passageway.
 7. The fluid-moving device of claim 6, wherein at least one fluid communication port is a fluid inlet and at least one communication port is a fluid outlet.
 8. The fluid-moving device of claim 7, further comprising a plurality of valve passageways formed inside the housing, wherein each passageway intersects the internal passageway and has a first end connected to the inlet or the outlet of the valve, whereby connecting the inlet and the outlet to the internal passageway, and a second end opened to the outside.
 9. The fluid-moving device of claim 8, further comprising a manifold attached to the housing, wherein the manifold comprises: at least one input port for connecting to a fluid supply; at least one output port for connecting to a fluid sink; and a plurality of manifold passageways formed in the casing and connecting the second ends of the valve passageways to the input or the output ports of the manifold.
 10. The fluid-moving device of claim 9, further comprising an elastomeric seal positioned between the valve and the manifold passageways.
 11. The fluid-moving device of claim 4, wherein a type of the valve is selected from the group consisting of face shear valves, diaphragm valves, and cup-type shear valves.
 12. The fluid-moving device of claim 1, wherein the housing of the fluid-moving device is made of two mating parts, each part having a suction cavity and an internal groove formed between the suction cavity and an outside surface of the housing, wherein the cavity and the groove on one mating part cooperate with the matching cavity and groove on the second mating part to form the suction chamber and the internal passageway.
 13. The fluid-moving device of claim 1, wherein the housing is made of a rigid material.
 14. The fluid-moving device of claim 13, wherein the rigid material is selected from the group consisting of metals and plastics.
 15. The fluid-moving device of claim 1, wherein the sealing member and the moving member are made of ceramic materials.
 16. The fluid-moving device of claim 1, wherein the gap is defined by an internal wall of the sealing member and an outer wall of the moving member, and cross-sections of the internal and the outer walls have substantially circular shapes.
 17. The fluid-moving device of claim 1, wherein the sealing member is integrally formed with the housing.
 18. The fluid-moving device of claim 1, wherein the sealing member is a separate element from the housing, the fluid-moving device further comprising a static seal disposed between the housing and the sealing member to maintain the fluid-tight relationship therebetween.
 19. The fluid-moving device of claim 18, wherein the static seal is an annular elastomeric seal removably mounted on the sealing member.
 20. A pump, comprising: a housing having an internal wall defining a suction chamber for containing a fluid; a valve attached to the housing; a piston movably disposed within the chamber; an internal passageway formed inside the housing, the internal passageway having a first end opening to the suction chamber and a second end connecting to the valve; and a sealing member circumferentially disposed between the housing and the piston, the sealing member having a fluid-tight relationship with the housing, and the sealing member and the piston defining a continuous and uniform gap, wherein the gap has a size that allows the fluid to fill the gap but prevents the fluid from flowing through the gap from the suction chamber to an outside of the chamber under an operating fluid pressure.
 21. The pump of claim 20, wherein the sealing member and the piston are made of ceramic materials.
 22. The pump of claim 20, wherein the housing comprises a bearing disposed inside the suction chamber, the bearing having an aperture, wherein the moving member disposed coaxially and slidably inside the aperture.
 23. The pump of claim 20, further comprising a static seal disposed between the housing and the sealing member to maintain the fluid-tight relationship therebetween.
 24. The pump of claim 23, wherein the static seal is an annular elastomeric seal removably mounted on the sealing member.
 25. The pump of claim 20, wherein the valve has at least one fluid communication port connected to the second end of the internal passageway.
 26. The pump of claim 20, wherein the valve is a face shear valve.
 27. A method of making a fluid-moving device, comprising: (a) providing a housing having a suction chamber; (b) movably disposing a moving member within the chamber; (c) forming an internal passageway, wherein a first end of the internal passageway opens to the suction chamber and a second end of the internal passageway opens to an outside surface of the housing; and (d) placing a sealing member between the housing and the moving member to result in a fluid-tight relationship between the sealing member and the housing, whereby the sealing member and the moving member define a continuous and uniform gap, wherein the gap has a size that allows the fluid to fill the gap but prevents the fluid from flowing through the gap from the suction chamber to an outside of the chamber under an operating fluid pressure.
 28. The method of claim 27, wherein the step of forming an internal passageway inside the housing, further comprises: making intersecting bores in the housing, each bore having an outer portion opening to the outside surface of the housing; and plugging the outer portion of each bore. 